Blf a6/astrolux s1 driver and xhp50

Hi! So I had this Idea of using the blf driver for powering an xhp50. I will be putting it in a light that requires a 17mm driver(maybe an s2+ or my thorfire vg10). There are tons of xhp50/70 drivers, but the smallest one I can find is the fx6 driver, at 22mm.
So I know the blf driver puts out 4-6 amps at max 4.2v, so I was thinking if I could connect 2 blf’s in series and make 8,2v for the xhp50? If not I could always direct drive it, but that’s inconvenient, and stuff would probably melt, haha. Thanks!

I wish it would work like that, but drivers in series AFAIK does not work.

Actually there are not many direct drivers for 6V leds, the one i know is from Mountain Electronics ( FET Driver - 2S+ Momentary - 17mm / 20mm ), but shipping to Europe for just a driver makes it pretty expensive. There’s enough interesting to find on his website so perhaps you can combine some stuff to make the shipping worthwhile.

hm, how about just straight from battery, if I use 2 18350’s. I know right, the shipping is more expensive than a driver from there, I checked out mtn, but It wasn’t worth it, actually found one of ebay just now, at 17mm, but it was only 4 amps, bummer. Thanks for the answer!

Can you give the ebay link for that driver?
4A (25W!) is massive for a XHP50 in a small host like you plan to use. and I wonder how much more than 4A you get anyway with 2x18350 cells.

http://m.ebay.co.uk/itm/0-10-Amp-capable-LED-Flashlight-driver-board-17mm-Cree-XHP70-XHP50-XML2-XPL-/201546868150?nav=SEARCH

Ah, that is the same driver that Mtn El. has made, but sold by vestureofblood (also a BLF member). The shipping costs do not make this driver any cheaper than via Mtn El.

no it does not, but we’ll see. How about a direct drive, straight from battery, would lose all modes,but ?

if I used 2 18350 10amp high drains, keeppower?

direct drive will work fine, but all the risk handling is transferred to the user (no low voltage protection, no reverse battery protection: led will blow instantly when battery is inserted the wrong way), and there’s just one mode.

I have made flashlights like that but in practice they see no use, I use lower modes way more often than full blast.

maybe I like it dangerous, haha, It would just be for a short amount of time, I like to run higher modes usually. I already have made some direct drive ones with single modes and they work fine.

I believe the BLF driver can be modified to operate at two cell. LDO + resistor mod. Someone correct me if I’m wrong. I’ve only done it with amc7135 drivers.

how would I do that though? It has a fet and one 7135, how do I add the resistor and where? What’s ldo a diode?

That is coincidently what I tried a week ago, but not with a LDO but with a zener diode: the so-called ‘zener-mod’ on a BLF-A6 driver. It did work in the sense that it did drive an XHP70 led in 2S configuration without killing the MCU, but the user interface and timings were completely messed-up so it was un-usable.

A zener mod on a 105C driver works well, with the user interface un-altered, but the low voltage protection kicks in at a too high voltage, at about half drainage of the cells.

just found an ld3 driver here on blf, and it’s in eu whohoo, this will be awesome.

You are right, forgot about the LD3 (and I even tested it :person_facepalming: ) , that is a great option too! Don’t forget to order it in 2S configuration.

can you run it of a single hg2

An XHP50 runs on 6V, a single li-ion is half of that. A driver that will do that is a so-called boost-driver. The LD3 is not a boost driver, so the battery voltage needs to be a bit higher than the led voltage.

Btw, single cell boost drivers for 6V leds usually have a limited current, you will not get the output of a lineair/direct driver in a 2S configuration.

allright, thank younso much!

Hmm… The LD3 is 3 or 6 amperes…
Can it do 4.5 Amperes?

If you read the LD3 info thread, you will find that a new feature in the LD3 is that there is a user configurable adjustment of the maxium output current, down to 2A off the listed current. So the 6V version can be configured down to 4A.